Server: NC 15.0.0, versions do not appear, TypeError: this.sync is not a function

[lecyril]

Following the advice of stratege1401 on nextcloud forum
Please bear with me, this is my very first bug report on github, I will try to do my best!

Steps to reproduce

1. Create a file
2. Make a change so a new version is created
3. Verify that a new file in /nextcloud-data/username/files-versions has effectively been created
4. In the web interface, click on Details -> Versions for that particular file

Expected behaviour

The list of previous versions of the file should appear.

Actual behaviour

Nothing is displayed.
The other tabs work normally: activity shows that the file has been modified, Share allows for sharing the file. Only "versions" does apparently nothing.
Output from Firefox and Chrome consoles (see below): TypeError: this.sync is not a function** core.js:2101:14. I can provide other details if needed.
It might be related to my php configuration, so I included a link to the whole phpinfo() below.

Server configuration

Operating system: linux / shared hosting

Web server: Apache

Database: 10.1.37-MariaDB

PHP version: 7.2.13 - see phpinfo

Nextcloud version: 15.0.0

Updated from an older Nextcloud/ownCloud or fresh install: Updated gradually since NC11 whenever updates were available

Where did you install Nextcloud from: From nextcloud.com web installer initially (NC11), then using auto-updater

Login as admin user into your Nextcloud and access 
http://example.com/index.php/settings/integrity/failed 
No errors have been found.

List of activated apps:

App list

Accessibility 1.1.0 Officielle
Activity 2.8.2 Officielle
Auditing / Logging 1.5.0 Officielle
Contacts 3.0.1 Officielle
Default encryption module 2.3.0 Officielle
External storage support 1.6.0 Officielle
Federation 1.5.0 Officielle
File sharing 1.7.0 Officielle
First run wizard 2.4.0 Officielle
Gallery 18.2.0 Officielle
Log Reader 2.0.0 Officielle
Nextcloud announcements 1.4.0 Officielle
Notifications 2.3.0 Officielle
Password policy 1.5.0 Officielle
PDF viewer 1.4.0 Officielle
Share by mail 1.5.0 Officielle
Support 1.0.0 Officielle
Text editor 2.7.0 Officielle
Theming 1.6.0 Officielle
Update notification 1.5.0 Officielle
Versions 1.8.0 Officielle

Nextcloud configuration:

Config report

$CONFIG = array (
  'instanceid' => 'XXX',
  'passwordsalt' => 'XXX',
  'secret' => 'XXX',
  'trusted_domains' => 
  array (
    0 => 'XXX',
  ),
  'datadirectory' => '/home/secondes/nextcloud-data',
  'overwrite.cli.url' => 'XXX',
  'dbtype' => 'mysql',
  'version' => '15.0.0.10',
  'dbname' => 'XXX',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'XXX',
  'dbpassword' => 'XXX',
  'logtimezone' => 'UTC',
  'installed' => true,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'debug' => false,
  'updater.secret' => 'XXX',
  'maintenance' => false,
  'enable_certificate_management' => false,
  'mail_from_address' => 'nextcloud',
  'mail_smtpmode' => 'smtp',
  'mail_domain' => 'XXX',
  'theme' => '',
  'loglevel' => 2,
  'updater.release.channel' => 'stable',
  'versions_retention_obligation' => 'auto',
  'mail_smtphost' => 'XXX',
  'mail_smtpport' => '465',
  'mail_smtpauth' => 1,
  'mail_smtpname' => 'XXX',
  'mail_smtppassword' => 'XXX',
  'mail_smtpsecure' => 'ssl',
);

Are you using external storage, if yes which one: no

Are you using encryption: yes

Are you using an external user-backend, if yes which one: No

Client configuration

Browser: Firefox 60.0.1 / Chrome 67.0.3396.87

Operating system: Windows 10

Logs

Web server error log

Web server error log

Nothing relevant to the error according to the timestamps

Nextcloud log (data/nextcloud.log)

Nextcloud log

Nothing relevant to the error according to the timestamps

Browser log

Firefox console, when I hit "Versions" on the web interface

    **`TypeError: this.sync is not a function** core.js:2101:14
fetch    https://XXX/core/vendor/core.js:2101:14
nextPage    https://XXX/index.php/js/files_versions/merged.js:270:4
setFileInfo    https://XXX/index.php/js/files_versions/merged.js:360:5
selectTab    https://XXX/index.php/js/files/merged-index.js:9972:4
_onClickTab    https://XXX/index.php/js/files/merged-index.js:9876:4
_onClickTab self-hosted:975:17 
dispatch    https://XXX/core/vendor/core.js:3:6414
add/r.handle    https://XXX/core/vendor/core.js:3:3224

[MonksterFX]

Same over here. Had a fresh installation, only with the default apps installed.

[lecyril]

I tried installing a new instance on another subdomain, and versioning worked as designed.
After fiddling around to find the differences between my live instance and the fresh one, I noticed that I had disabled the _Comments_ application on the former.
Re-enabling _Comments_ app restored the versioning functionality. Disabling it again broke it.
So at least in my particular settings, disabling the Comments app breaks versioning app in the web interface.
Problem solved on my side, but you might want to confirm whether this is an actual, general bug.
Thanks for the fantastic work developing Nextcloud,

Cyril

EDIT: I was indeed able to reproduce this on demo.nextcloud.com

[JochenHWezel]

Same to me: no older versions appear in the expected list:

My NextCloud instance is v15.0.0 running with mysql database.

My Chrome console found following errors on opening/reloading the directory list at https://xyz-host/cloud/index.php/apps/files/?dir=/abc%20Allgemein&fileid=15:

The activity tab correctly notes that there was a change:

The Comments app is still activated in my instance, also deactivation+re-activation didn't solve the issue:

Versions app is activated, also deactivation+re-activation didn't solve the issue:

[ghost]

Same to me with Nextclud 15.0.2.

Versions are stored in users files_version directory properly

but neither appear in the browser nor appear e.g. in collabora (i.e. gewicht.xlsx).

Nothing was written to the nextcloud.log.

Debian Stretch 9.6 64Bit
Nextcloud 15.0.2
NGINX 1.15.8 TLS 1.3
PHP 7.3
MariaDB 10.3
Redis

files_versions: 1.8.0

In the browser console i received:

TypeError: this.sync is not a function[Weitere Informationen] core.js:2101:14
fetch
https://my.cloud.org/core/vendor/core.js:2101:14
nextPage
https://my.cloud.org/js/files_versions/merged.js:270:4
setFileInfo
https://my.cloud.org/js/files_versions/merged.js:360:5
selectTab
https://my.cloud.org/js/files/merged-index.js:9972:4
_onClickTab
https://my.cloud.org/js/files/merged-index.js:9876:4
_onClickTab self-hosted:974:17 dispatch
https://my.cloud.org/core/vendor/core.js:3:6414
add/r.handle
https://my.cloud.org/core/vendor/core.js:3:3224

while selecting the versions in firefox 64.0.2 (64Bit).

Using Edge the console throws:

[felixn]

I have the same issue in Nextcloud 15.0.2.
The Versions tab is empty, console shows:
TypeError: this.sync is not a function[Learn More] core.js:2101:14

Enabling the Comments App fixes the issue & the Versions tab works as expected.

[ghost]

i can confirm. enabling the comments app fixed the issue. great - thanks.

[Omnimercador]

In my case, the Comments App was already active, and the Versions tab didn't appear.

Deactivating and reactivating the Versions App resolved the issue

[parthdmaniar]

I agree with @Omnimercador, I enabled comments application. Disabled and re-enabled version application. I can see the versions of file now. Works perfectly. :)

[adaigre]

Same problem here ! Thanks for the workaround.
When would it will be fixed ?

[lecyril]

The issue can still be easily reproduced on demo.nextcloud.com (15.0.4 as of today).

• Create a demo instance and log into it with admin/admin
• Disable Comments app
  -> Version tab is broken (blank)
• Enable Comments app
  -> Versions work as expected
• Disable Comments app to reproduce again... I don't think that it is necessary to disable/enable the Versions app for reproducing or fixing the bug.

[felixn]

I'm trying to find the cause of this, but it's slow progress.
What I've found so far:

• return this.sync('read', this, options); fails
• this is VersionCollection, but this.sync is undefined
• sync is set here, but OC.Backbone.davSync is undefined: https://github.com/nextcloud/server/blob/1cfa870821c92bdd6854171c8c073ed16529b6df/apps/files_versions/src/versioncollection.js#L17

When I enable the versions app, oc-backbone-webdav.js gets loaded and OC.Backbone.davSync gets set correctly -> versions tab works as expected.
I haven't figured out what affects whether oc-backbone-webdav.js gets loaded...

[juliushaertl]

Fixed with #14472